There may be as many as 80,000 American prisoners currently locked-up in a SHU, or segregated housing unit. Solitary confinement in a SHU can cause irreversible psychological effects in as little as 15 days. Here's what social isolation does to your brain, and why it should be considered torture.

There's no universal definition for solitary confinement, but the United Nations describes it as any regime where an inmate is held in isolation from others, except guards, for at least 22 hours a day. Some jurisdictions allow prisoners out of their cells for one hour of solitary exercise each day. But meaningful contact with others is typically reduced to a bare minimum. Prisoners are also intentionally deprived of stimulus; available stimuli and the fleetingly rare social contacts are rarely chosen by the prisoners, and are are typically monotonous and inconsiderate of their needs.

As for the jail cell itself, it typically measures 6' x 10'. Nearly all scenarios for human contact, such as a guard, or medical and family visits, are done through a metal mesh, behind glass partitions, or in hand- and leg-cuffs.

What's emerged from the reports and testimonies reads like a mix of medieval cruelty and sci-fi dystopia. For 23 hours or more per day, in what's euphemistically called "administrative segregation" or "special housing," prisoners are kept in bathroom-sized cells, under fluorescent lights that never shut off. Video surveillance is constant. Social contact is restricted to rare glimpses of other prisoners, encounters with guards, and brief video conferences with friends or family.

For stimulation, prisoners might have a few books; often they don't have television, or even a radio. In 2011, another hunger strike among California's prisoners secured such amenities as wool hats in cold weather and wall calendars. The enforced solitude can last for years, even decades.

These horrors are best understood by listening to people who've endured them. As one Florida teenager described in a report on solitary confinement in juvenile prisoners, "The only thing left to do is go crazy."

Prisoners in low and medium security jails are often thrown in the SHU for "just" a few days. But in maximum security prisons, individuals in solitary are held on average for five years, and there are thousands of cases of prisoners who have been held in solitary confinement for decades. Some countries, including the United States, employ the use of Super Maximum Security Prisons, or "Supermax Prisons," in which solitary confinement is framed as a normal, rather than exceptional, practice for inmates.

Exact statistics are not known, but a 2011 study suggested that 20,000 to 25,000 prisoners in the United States are held in this way. Keim claims that that California holds some 4,500 inmates in solitary confinement, and that there are as many as 80,000 prisoners held in solitary across the United States — more than any other democratic nation.

Lasting Effects

Human beings are social creatures. Without the benefit of another person to "bounce off of," the mind decays; without anything to do, the brain atrophies; and without the ability to see off in the distance, vision fades. Isolation and loss of control breeds anger, anxiety, and hopelessness.

Depression: Emotional flatness/blunting and the loss of ability to have any "feelings", mood swings, hopelessness, social withdrawal, loss of initiation of activity or ideas, apathy, lethargy, major depression

Perceptual distortions: Hypersensitivity to noises and smells, distortions of sensation (e.g. walls closing in), disorientation in time and space, depersonalization/derealization, hallucinations affecting all five senses (e.g. hallucinations of objects or people appearing in the cell, or hearing voices when no one is speaking

Paranoia and psychosis: Recurrent and persistent thoughts, often of a violent and vengeful character (e.g. directed against prison staff), paranoid ideas (often persecutory), psychotic episodes or states, psychotic depression, schizophrenia

Self-harm: self-mutilation and cutting, suicide attempts

In California, it has been shown that inmates are 33 times more likely to commit suicide than other prisoners incarcerated elsewhere in the state. Disturbingly, solitary confinement beyond 15 days leads directly to severe and irreversible psychological harm. But for some, it can manifest in even less time. What's more, a significant number of individuals will experience serious health problems regardless of specific conditions of time, place, and pre-existing personal factors.

In terms of prevalence, somewhere between 8% and 19% of American prisoners will experience significant psychiatric or functional disabilities, while another 15% to 20% will require some form of psychiatric intervention during their incarceration. Figures in Europe are comparable. The American Psychiatric Association says that up to 20% of all prisoners are "seriously mentally ill" whereas up to 5% are "actively psychotic at any given moment." About 4% of inmates have schizophrenia or some other psychotic disorder, nearly 19% suffer from depression, and around 4% have bipolar disorder (Abramsky and Fellner 2003).

Once Considered Rehabilitative

Ironically, solitary confinement began with the best of intentions.

It emerged in the United States during the 1820s when it was believed that isolating prisoners would be rehabilitative. They thought that prisoners would spend their entire day alone, mostly within the confines of their cells, ruminating about their crimes while distanced from negative external influences. European and South American countries eventually adopted the practice. At the time, solitary confinement was perceived as a socially and morally progressive way to deal with punishment — and a viable alternative to the death penalty. (image: Eastern State Penitentiary, Library of Congress)

Today, people are put into the SHU for breaking prison rules, or for "administrative reasons" such as interrupting gang communications, protecting other prisoners, or to separate the prisoner from others who would threaten them.

This is simply not true. Many if not most people in solitary confinement suffered from mental illness prior to their placement in solitary; responding to their disruptive behavior is not only a failure of the prison mental health systems to provide minimally required care, but also exacerbates their conditions and typically leads to even worse problems.

Sadly, and despite the US Supreme Court ruling that placing mentally ill individuals in solitary confinement is a constitutional violation, the practice is still widespread; most mentally ill prisoners cannot seek recourse. Weirdly, the Supreme Court has not refused to rule it unconstitutional to keep someone in solitary who has become mentally ill because of the experience.

What's more, solitary confinement is also a racial issue. A 2005 BJS prison census showed that non-white prisoners are substantially overrepresented in supermax facilities. As Margo Schlanger writes in Solitary Watch, "American jails and prisons are themselves vastly racially skewed in their populations, and what we are likely to find is an even more extreme skew for those who are on the receiving end of isolated confinement's harsh effects."

This investigative report, "Boxed In: The True Cost of Extreme Isolation in New York's Prisons," was put together by the New York Civil Liberties Union (more here). .

Putting An End to It

Solitary confinement fails as a rehabilitative measure, and as a way to "settle down" problematic prisoners. The practice actually backfires, causing prisoners to lose their ability to control their anger, which can result in a longer stint in solitary. And as the devastating laundry list of psychological disorders can attest, it needs to be called out for what it is: torture.

The United Nations agrees. Back in 2011 it issued a report claiming that long-term solitary isolation is a form of torture — a cruel, inhuman, and degrading treatment prohibited by international law. The report made special reference to the United States' use of supermax prisons as a violation.

"Segregation, isolation, separation, cellular, lockdown, Supermax, the hole, Secure Housing Unit… whatever the name, solitary confinement should be banned by States as a punishment or extortion technique," noted the UN's Juan E. Méndez. "Social isolation is one of the harmful elements of solitary confinement and its main objective. It reduces meaningful social contact to an absolute minimum."

In the US, a number of groups are now railing against the practice, including the New York Civil Liberties Union, the Center for Constitutional Rights, and Human Rights Watch. Two years ago, the US Senate held its first-ever hearings on solitary confinement, concluding that the practice is ineffective and a costly human-rights violation. In fact, it's the most expensive form of incarceration, costing up to three times as much as general prisoner population housing.

And as Alexis Agathocleous from the Center for Constitutional Rights has aptly noted:

We know that keeping someone in solitary confinement puts them at very serious risk of descending into irreversible mental illness. That's not tolerable in a society that values the dignity and humanity of all people, no matter whether they are incarcerated or not.